Hollow article and method and apparatus for producing the same



May 10, 1949. D. G. REMPEL 2,469,892

HOLLOW ARTICLE ANDI METHOD AND APPARATUS FOR PRODUCING THE SAME FiledSept. 10, 1947 4 Sheets-Sheet 1 May 10, 1949. D. G. REMPEL 2,469,892

HoLLow ARTICLE AND METHOD AND APPARATUS FOR PRoDUcING THE SAME FiledSept. 10. 1947 4 Sheets-Sheet 2 INVENTOR. .Dielrlclr G. Fem/oel BY EHarney May l0, 1949. D. G. REMPEL HOLLOW ARTICLE AND METHOD ANDAPPARATUS FOR PRODUCING THE SAME Filed Sept. l0, 1947 4 Sheets-She'et 4fborney Patented May 10, 1949 HOLLOW ARTICLE AND METHOD AND AP'PA- RATUSFOR PRODUCING THE SAME Dietrich G; Rempel, Akron, Ohio, assig'nor tollempel Enterprises, Akron, hio, a partners ip Application September 10,1947, Serial No. 773,209

1s claims. (cris-2s) y This invention relates to a method and apparatusfor producing hollow articles, land particularly for producing hollowarticles by deposition of liquid rubber or other aqueous dispersionmaterial.

In the past various attempts have been made to form hollow rubberarticles, for example, by socalled rotary casting methods, but theseattempts have not been completely successful and for that reason rotarycasting methods have not been generally accepted for large scaleproduction. The accepted practice followed formanufacturing such hollowarticles at present utilizes what is known as the blown Vulcanizingmethods, wherein preformed hollow biscuits of sheet rubber stock areformed in sectional cavity molds, under the influence of heat andinternal pressure. These blown methods, however, require extensivefactory floor space to accommodate a vast amount `of necessaryequipment.

The invention herein utilizes a process by which a predeterminedquantity of latex or similar aqueous dispersion material is placed in aplaster of Paris mold, which mold is given a compound rotary motion toform an article by depositionv of the latex on the mold cavity surface,and thereby to form a complete hollow article of substantially anydesired shape and predetermined wall thickness, without excessdeposition material. In the development of the invention, however, ithas beenv found that if ,certain conditions prevail pertaining tomoisture content -of the mold either the product or the process, orboth, may not be entirely satisfactory. As an example, under certainconditions in production, as between the time articles lare removed fromthe mold after one cycle of operation and refilling of the mold withlatex for the next succeeding cycle of operation, drying action may takeplace at both the inner and outer surfaces of the mold, and result in alayer of moisture intermediate said inner and outer surfaces. Thus,

` when the mold is refilled with latex as described,

air will vbe trapped between said intermediate moisture layer and amoisture layer at the inner surface of the mold, from the newly suppliedlatex. A substantial proportion of this trapped air cannot escapeoutwardly of the mold because of the intermediate moisture layer and isforced into the mold cavity and the product being formed therein,resulting in air bubbles, blisters, and holes in the product. If, on theother hand, the plaster mold is maintained somewhat saturated to thefull wall thicknesses thereof, with capillary movement of the wateroutwardly maintained in. norm-al course, a satisfactory product mayresult,`but the article-drying process necessary to permit opening ofthe mold and removal of the formed 'article is extremely slow (48 hoursfor example). If the mold is in bone dry condition, whenthe initialdeposition is started, the capillary movement of the water from thelatex will alsobe maintained outwardly, in normal course, and asatisfactory product may result; when such a bone dry mold is used thenished product may be removed within from six to eight hours. Ittherefore, becomes self-evident that for successful use of such rotarycasting methods, it is necessary to provide controlled variance ofmoisture and dryness in different portions of the mold.

One object of the present invention is to provide a process formanufacturinghollow articles utilizing the above described principle ofdeposition of rubber latex or like aqueous dispersion material,including improved steps and apparatus for controlling capillarymovement of water through the-porous mold so that it is constantlyoutward, whereby is produced goods of highquality, free of pockmarks,depressions or holes.

Another object of the invention is tovprovide an improved method andapparatus capable of producing commercially acceptable hollow rubber orlike articles of the character described, in a manner which obviates thenecessity for the use of certain equipment normally required, such asrubber mills, vrubber reworking machines, article preforming equipment,heavy vulcanizing molds and presses, vulcanizing heat and pressuresupplying equipment, as well as other equipment and supplies usuallyincidental to the employment of the blown rubber methods.

I Another object of the invention is to provide an effective, eflicientand economical procedure for manufacturing hollow articles by depositionof article-forming materials in a cavity mold, wherein the finishedarticles thereby produced will have substantially uniform predeterminedwall thickness as desired and without marks or blemishes on the outersurfaces thereof.

Another object of the invention is to provide a rotary casting method ofthe character described utilizing predetermined quantities of liquiddeposition material for forming each article without excess of thematerial, and thereby making possible the ruse of multiple-cavity moldswhich are also adapted to be in stacks thereof during the rotary castingmovements.

Another object of the invention is to provide a method for producinghollow rubber articles of the character described by deposition ofrubber material in a mold cavity surface, wherein the articles will besubstantially completely formed and non-porous upon removal thereof fromthe mold cavities, without requiring the use of heat and pressure andwithout requiring the use of swelling or other treatments to close poresin the material.

Another object of the invention is to provide a method and apparatus forproducing completely closed hollow rubber articles particularlysuitable, for example, to be used as so-called bathtub toys.

Another object of the invention is to provide an improved method andapparatus by Which may be produced hollow rubber articles ofsubstantially any shape, irregular or otherwise, and by which thearticle-forming material is conformed effectively to undercut portionsor sharp corners of an article-forming mold.

These and other objects of thev invention will be manifest from thefollowing brief description and the accompanying drawings.

This application is a continuation-impart of co-pending application'lSerial Number 683,335, led July 13, 1946.

Of the accompanying drawings:

Figure 1 is a compositeplan View illustrating a suitable arrangement ofequipmentfor carrying out the method of the invention.

Figure 2 is a side elevationof a machine for applying a preliminarycompound rotary motion to an article-forming mold, in accordance withthe method of the invention.

Figure 3 is a top plan view of a machine for applying a subsequent orsecondary compound rotary motion to the mold or molds.

Figure 4 is a frontl elevation of the machine shown in Figure 3. v

Figure 5 is a side elevation, partly broken away and in sectionillustrating apparatus for conveying and treating the molds receivedfrom the machine of Figures 3 and 4.

Figure 6 is a fragmentary cross-section of a lower mold section,illustrating the step in the method prior to application of rotarymotion thereto, wherein a predetermined volume of latex is placed in themold cavity.

Figure 7 is a similar fragmentary cross-section through the closed mold,after a preliminary compound rotation thereof in the apparatus of Figure2.

Figure 8 is a view similar to Figure 7, partly broken away, illustratingthe completely formed articles in the closed mold, after it has beensubjected to a secondary compound rotary motion in the machine ofFigures 3 and 4.

Figure 9 is a fragmentary cross-section, corresponding to Figure 6, butillustrating a device provided in the mold for forming a whistleaperture in an article deposited therein.

Figure 10 is a view similar to Figure 9, and corresponding to Figure 8,illustrating the article completely formed with the whistle aperturetherein.

Figure 11 is an elevational view of a completed hollow rubber article,partly broken away and in section, after removal of the samefrom themold of Figure 8. v

The improved method may -be `best described in connection with theoperationand use of equipment 'illustrated in certain'V figures of thedrawings. Referring particularly to Figure 1 thereof, there isillustrated semi-diagrammatically, apparatus for carrying out the methodof 4 the invention, the same including a latex measuring and supplyingdevice A, a primary mold rotating machine B, one or more secondary moldrotating machines C, mold conveying and treating equipment D, articlereceiving racks E, and

a drying or curing chamber F.

In carrying out the method as for example to v produce ahollow rubbercharacter animal G of the type best illustrated in Figure 11, the lowerhalf or section 20 of a two-part cavity mold 2l, of plaster of Paris,clay, or like porous material, is mounted on a horizontally positionedplate 22, o! a mold support 23 of the mold rotating machine B (seeFigure 2), the plate 22 being journalled in a. sleeve 24 to rotate on ahorizontal axis, and the sleeve 24 being'pivotally mounted at 25 tosupporting bracket 26 to be swingable to move the mold support 23 towardand from the latex measuring and supplying device A. In the chaindottedposition of the mold-supporting plate 23, indicated at` B1 in Figure 1,a predetermined volume of rubber latex. 'I'he term latex herein includeslatex, or like aqueous dispersion of rubber or synthetic elastomer, issupplied to each of a plurality of article-forming cavities 23a, 23a inthe lower mold half 20, as indicated at 21v in Figure 6.

Immediately upon supplying said predetermined volumes of latex 21 to thelower mold cavities the mold-holding apparatus B is swlmg away from thefilling device A, to a position in which the upper mold section 20avvmay be readily placed in registry on the lower mold section 20, and thena releasable clamping device 29 is operated with respect to the support23 to retain the mold sections thereon in tightly closed relation. Inthis last-named closed position of the mold it is engaged between a disc30 rotatably mounted on the plate 22 and a coaxial disc 3l yieldinglyand rotatably mounted on the shiftable clamping device 29, the commonax'is of the discs being at right angles to the axis upon which thesupport 23 rotates in sleeve 24.

Immediately after filling the lower mold cavities with the latex 21 theclosed mold 2| may be manually rotated relatively of the support 23about said axis of the discs, either independently or simultaneouslywith manual rotation of said support 23 about the axis of the sleeve 24,therebyapplying a compound rotary movement to the mold about the twoaxes. 'I'he time elapsing between supplying the latex to the mold andcompletion of the above described preliminary rotation of the closedmold may be a matter of only a, few minutes, one and one-half minuteshaving been found satisfactory in the use of synthetic rubber latex.Although this preliminary compound rotary movement preferably is carriedout as quickly as possible after the latex pouring step the rotary.motion itself is maintained slow enough that bubbles will not form onthe mold cavity surface, and to obviate such whipping action which wouldcause yfoaming of the latex. 'I'he rotary movement described iseffective to spread a thin preliminary deposit or skin-coating of thearticle-forming material 21 about the sur- 'faces of the mold cavitiesto build up fully shaped the surfaces of the fluid bodies of latextherein' (see Figure 6). The formation of such defects in the mannerdescribed is extremely objectionable, as in most instances they renderthe articles commercially unacceptable.

When once the preliminary skin-coatings 32 have been deposited about theinterior of the mold cavities as best illustrated in Figure 7, thesecondary rotary article-forming step may be accomplished in a moreleisurely manner in one of the mold rotating machines C (see Figures 1,3 and 4). Accordingly, while the preliminary mold rotating action istaking place the mold rotating device B may be shifted to the full-lineposition thereof shown in Figure l, to be relatively closely adjacentthe secondary mold rotating machines C. At this point the closed mold 2|is removed from the mold-holding device 23, and while the sections cfthe mold are retained in close registering position for placement in therotating machine C for a secondary relatively slow compound rotarycasting operation, a plurality of such molds 2| may be placed in amachine C in a stack, as made possible by said preliminary compoundrotation step.

In the present instance the machine C is illustrated as containing fivesuch molds, the same being stacked between spaced end plates 35 and 36,coaxially rotatably mounted onspaced crosspieces 31 and 38 of arectangular frame 39, which is in turn supported on spaced brackets 40and 4| to rotate about a horizontal axis at right angles to the axis ofrotation ofthe plates 35 and 36. The cross-piece 38 may be releasablyshiftable outwardly of the frame, by suitable 1 means as shown orotherwise, to permit such stacking or removal of molds fromvthe frame. Asuitable device 4 la is provided in association with plate 36 to applyclamping action thereto for holding the molds tightly together. Adjacentmolds of the stacks thereof may have small spacers 23h, 23h therebetweento permit substantially free circulation of air around each mold, aswill be described later, and to facilitate handling of the separatemolds. For rotating the mold supporting frame 39 about its horizontalaxis, a relatively fixed shaft extension 42 therefrom has a gear 43keyed thereto to be dritten, through a chain 44 and sprocket 45 bysuitable motor 46. To the end that the molds 2|, together with thc discs35 and 36, may be rotated about an axis angularly of said horizontalaxis, a shaft extension 41 from disc 35 has a bevel gear connection 48with a shaft 49 carried by the frame 39, and a spur gear 5U on a freeend of the shaft 49 engages a xed relatively larger gear 5| securedtothe fixed support 4|. This arrangement is such that as the motor 46drives gear 43 to rotate'the frame 39 about the horizontal axis, thisrotational movement of the frame carries spur gear 59 around fixed gear5|. said gear 50 thereby being driven to rotate shaft 49, and throughVbevel gears 48 applying rotary motion to the molds about an axis atright angles to the axis of rotation of the frame 39. The compoundrotary motion thus attainedin machine C is relatively slow, asl forexample approximately oneA revolution per minute vabout each of the twootherwise in accordance with particular conditions or requirements; Thecompound rotary action provided by the vmachine C is effective todeposit the remainder of the article-forming latex body 2l about theinterior of the mold cavities, over the previously depositedskin-coating 32, and thereby forming complete hollow articles G ofpredetermined uniform wall thickness (sec Figures 8, 10 and 11).

The time required to complete this secondary compound rotational stepmay vary according to conditions, such as differences in thecharacteristics of the deposition material, desired thickness and sizeof the completed article, etc., but in actual full scale production ofrubber toys of one type (see Figure. 11) by the present method it hasbeen found that latex deposition to full thickness may be accomplishedin approximately forty-five minutes.

It has been found also that in forming hollowV rubber articles inparticular, the setting or gelling action of the latex on the moldcavity surface is relatively rapid during the initial compoundrotational movements of the mold, and that as the rotational moveme-ntis continued the rate of speed of the setting or drying action becomesslower and slower until it levels 01T to a constant relatively slowsetting action. This no doubt accounts for the improved success of thepresent method attained by providing a preliminary quick compoundrotational movement of the molds to deposit a skin-coating, asdescribed. That is, the tendency for the latex to adhere to the moldcavity at the surface of the latex body in the mold would be at amaximum immediately after the latex is poured into the mold.

After the secondary compound rotary action has been completed, machine Cis stopped and the stack of molds is removed therefrom and placed on anintermittently operable conveyor 55, incorporated in equipment D shownin Figures 1 and 5. Conveyor 55 is in the natureof a progressivelymovable storage space, the same being operable to move mold stacks'fromone end of the conveyor to the other within a substantial period of timeduring which articles G in the respective molds will, by continuedcapillary removal of moisture from the deposited rubber through thepores of the molds, dry or set suillciently to permit opening of themolds and ready removal of the articles therefrom without damage, at theleading end of conveyor 55 (see araxes. preferably with. a slightdifferential 'in the v speeds about the respective axes to assurecomplete uniform latex coverage of fall cavity surface areas. iHighlysatisfactory results have been attained by rotating the mold onerevolutionper minute about one axis and one and one quarter.'

revolutions per minute about the other; axis, or'

rows in Figure 5). Thisstep in the process, termed the pre-drying stage.may take about eight hours (for` synthetic rubber). In other words. wheneach article is fully formed. by deposition or accretion of latex withinits mold cavity, and is ready for removal from the mold, substantiallyall Water from the initial predetermined, quantity of latex 21 will havepassed outwardly of the mold cavity by capillary attraction. through amyriad of pores in the mold material. the Water being dissipated at theouter mold surfaces by evaporation. This substantially complete removalof water from the deposited latex (see Figure 8). together with theabove referred. to adhesion-of the formed article to the mold cavitysurface. no doubt accountsA 'for the subsequent slight shrinkage whichhas been found to be substantially the same as the normal shrinkage ofmolded rubber articles made by blowing methodsv (about two per cent).

In connection with the pre-drying stage of the lmethod it is nownecessary to consider the previously described problem of damaged goodscaused by formation of air bubbles, particularly during the latexdeposition stage or stages. It has been found in actual practice thatsuch conditions will be obviat-ed if the capillary movement of waterfrom the deposited latex'is maintained continuously outward through themold, from thc cavity thereof, at all times while the deposited latex isin the molds. To this end, there may be provided over and around theconveyor 55, a heat-insulatcd hood or housing 56, having suitableopenings l at opposite cnds thereof to permit passage of the stacks ofmolds carried by the conveyor. Heated, air is blown from a suitablesource (not shown), through conduits 57, 57, to the interior of housing5B and outwardly through a conduit 5B, thereby circulating the airaround the stacks of porous molds. A suitable temperature for the airfor the present purposes is approximately 90 F. A temperatureapproximating 120 F. or over may cause expansion from within thecompletely formed hollow articles, which would force the molds open andthereby damage the articles. This moderately heated air, then, incirculating around the molds, including the spaces between adjacentmolds as provided by spacers 23h, all during the pre-drying stage, willmaintain the molds relatively dryer on the outside than on the inside(from the cavity surfaces), and as long as there is water in the latexdeposits such water will be steadily dissipated outwardly by capillaryattraction and evaporation and no wet layers or strata will be createdto cause formation of recesses and holes in the articles, as previouslydescribed. This treatment of the molds, of course, is important forpreparing the same for each succeeding article-forming cycle, becausethe mold will then have no localized water-saturated areas creating airpockets outwardly of the cavity surfaces, and when succeeding latexsupplies are placed in the molds the molds will again be desirablywetter inside than out and the capillary movement of the Water will bemaintained continuously or at least consistingly outwardly as long asthere is water in the latex or latex deposits.

After the molds have been on conveyor 55 the requisite length of time,as set forth above, they are removed and opened by suitable means (notshown) and the full-formed articles are removed therefrom, the moldhalves being returned to the dispensing machine B, on conveyors 59, 59.The removed articles G may be placed on suitable racks E, which are thenplaced in a drying or vulcanizing chamber or oven F at sufficiently hightemperature to complete the curing cycle.

The internal structure of the porous mold may be considered as cellularand comprising interconnecting microscopic tubes or passages which carrywater by capillary attraction from the cavity surfaces to the outersurfaces of the mold. Any condition of the mold in which the mold cavitysurface is maintained wet and water in these tubes or passages extendscontinuously from the cavity surfaces. that is with no air-trappingpockets between said inner and outer mold surfaces, will result in thewater or moisture from thc deposition material or deposited articlebein;r continuously dissipated outwardly of the mold cavity by capillaryattraction and evaporation, without creating air bubbles resulting indefective goods. In order that there Will be no interruption in thiscontinuous outward capillary movement of the water, which would createen adverse condition as previously described, it is important tomaintain at a minimum the period between the opening of each mold at thedelivery end of conveyor 55, for removal of the articles therefrom, andrefilling and closing the mold at dispensing machine A. In continuousoperation of the process, .utilizing return conveyor 59, when thisperiod was maintained at approximately five minutes satisfactoryarticles were produced.

Although it is 'possible and practical to form completely closed hollowrubber toys, or so-c'alled bathtub toys, by the present method, when thedescribed drying or vulcanizing step in chamber F is utilized arelatively small vent aperture 6i is necessary in each article toprevent bursting thereof due to internal expansion caused by the hightemperature of the chamber. The completed article is best shown inFigure 11.

Aperture 6I may be provided in each article, immediately after it isremoved from its mold, as by use of a rotary or other punching tool (notshown). As illustrated in Figure 9, the aperturepunching step may beeliminated by provision of a pin 62 of metal or other non-porousmaterial in each mold, the same projecting inwardly of the mold cavitysurface a distance corresponding to at least the desired thickness ofthe article. Thus, when the latex is deposited on the mold cavitysurface there will be little or no latex deposited on the pin (seeFigure 10), and when the completed article is removed from its mold thepin or insert 62 will have formed a substantially perfect aperturethrough the wall thereof. The aperture 6i is shown formed on the foot ofarticle G of Figure 11, although it may be provided on any part of thearticle, and this aperture may be utilized for installation of a metalwhistle or noise-maker, in known manner.

When relatively high vulcanizing heat is applied in chamber F asdescribed to shorten the curing period, the pressures internally andexternally of the articles will be the same, due to the provision ofvent apertures 6I. Any shrinkage which occurs in the articles afterremoval thereof from the molds is relatively slight and is substantiallyuniform, regardless of the shapes of the particular articles beingproduced. Character animals or other hollow articles produced by theherein described method will have substantially uniform Wall thicknessthroughout.

It will be seen from the above described angular velocities of the moldsabout angularly disposed axes (approximately one revolution per minute)and the length of time required to complete the deposition process, thatsuccessive compound rotations of the molds will progressively apply asubstantial number of latex laminations, layer-uponlayer in each moldcavity, conforming accurately to the shape thereof. That is, eacharticle G is built up of a series of laminations produced by layeringlatex solution onto the mold cavity surface with said compoundrotations. Because the unused latex retains all of its water untildeposition or accretion thereof takes place, it flows freely during thecontinued compound rotations of the molds and conforms accurately to theshape of every part of each mold cavity, including undercut portions ofreentrants, sharp corners, and even such small parts as the ears, horns,tail, teats, etc. of the cow shown in Figure 8. will be hollow and ofsubstantially uniform wall thickness as compared with the other parts ofthe article. When all of the latex 21 has been used up and the abovedescribed self-curing procedure of the article in the mold has beencompleted, substantially all of the water will have been removed fromthe deposited latex. Upon removal of the article from the mold,therefore, it will be of substantially the same size and configurationas the mold cavity. Any shrinkage which takes placel with furthervulcanization of the article (at room temperatures or otherwise), willbe ata minimum. The completed articles are seamless, as distinguishedfrom articles made from preformed plural .part biscuits of sheet rubberin the use of blowing methods.

Although the improved process has been described particularly inconnection with the production of hollow rubber character animals, itmay be similarly employed for producing other hollow articles such asrubber balls, athletic ball bladders, etc.

Similarly, the improved process may be successfully employed in theproduction of articles other than rubber, when the m". terial thereof isadapted Ito be supplied as an aqueous solution and lends itself tosetting through dehydration by capillary attraction in a porous mold. 1y

The herein describedmethod in accomplishing the stated objects of theinvention makes possible the production of hollow articles whichcouldrnot be produced heretofore by other known methods,

particularly in multiple cavity molds or stacks of such molds. Theresulting products are not only of superior quality but can be producedat greatly reduced cost, as compared with said known prior methods.

Modifications of the invention may be resorted to without departing fromthe spirit thereof or the scope of the appended claims.

What is claimed is:

1. A method of making hollow articles, comprising the steps of providinga plurality of sectional molds of porous material, each mold having aplurality of article-forming cavities therein and each cavity beingsupplied with a predetermined volume of aqueous dispersion materialsufiicient for forming an article of desired wall thickness, and whilemaintainingsaid molds in stacked relation applying compound rotarymotion to the stack about a plurality of angularly disposed axes todeposit the predetermined volumes of dispersion material in successiveaccreted layerings over the surface portions of the respectivearticle-forming cavities in diverse directions of flow of the dispersionmaterial, whereby said deposition and accretion of the dispersionmaterial is accomplished by removing water from the dispersion materialby capillary attraction outwardly through the mold pores and evaporationat the outer mold surface portions.

2. A method of making hollow articles comprising the steps of providinga sectional porous mold having an article-forming cavity adapted tocontain a liquid in all positions of rotation thereof and being adaptedto be opened and closed, placing in said article-forming cavity apredetermined quantity of aqueous dispersion material capable of settingby removal of water therefrom, and thereafter applying to said closedmold a series of compound rotary motions about a plurality of angularlydisposed axes to deposit said predetermined quantity of the aqueousdispersion material in successiveaccreted layerings over the surfaces ofthe mold cavity 'in diverse directions of flow of the dispersionmaterial, whereby said deposition and accretion is accomplished byremoving water from the dispersion material by capillary attractionoutwardly through the mold pores and evaporation at the outer moldsurface portions.

3. A method of making hollow articles coni= prising the steps ofproviding a sectional porous mold having an article-forming cavityadapted to contain a liquid in all positions of rotation thereof andbeing adapted to be opened and closed, placing in said article-formingcavity a predetermined quantity of latex aqueous dispersion materialcapable of setting by removal of` water 4. A-method of making hollowarticles comprising the steps of providing a sectional porous moldhaving an article-forming cavity adapted to contain a liquidin allpositions of rotation thereof and being adapted to be opened and closed,4placing ln said article-forming cavity a predetermined quantity oflatex aqueous dispersion material capable of setting by removal of watertherefrom, and substantially immediately thereafter applying compoundrotary motion to said mold about a plurality of vaxes to deposit aninitial coating of the dispersion material over the entirearticle-forming surface of the mold before suflicient time has elapsedfor the dispersion material to set over less than the entirearticleforming surface of said cavity, thereafter applying to said moldadditional compound rotary motions about a plurality of axes to depositthe remainder of said aqueous dispersion material in successive accretedlayerings over said skin coating in diverse directions of flow of thedispersion material, whereby said deposition and accretion isaccomplishedby removing Water by capillary attraction outwardly throughthe mold pores and evaporation at the outer mold surface portions.

-5. Av method of making hollow articles comprising the steps ofproviding a sectional porous mold having an article-forming cavityadapted to contain a liquid in all positions of rotation thereof andbeing adapted to be opened and closed, placing in said article-formingcavity a predetermined quantity of latex aqueous dispersion materialcapable of setting by removal of Water therefrom, applying to saidclosed mold a series of compound rotarymotions about a plurality ofangularly disposed axes to .deposit said predetermined quantity of theaqueous dispersion material in successive accreted layerings over thesurfaces of the mold cavity in diverse directions of flow ofthe-dispersion material, whereby said dep-` osition and accretion isaccomplished by removing water from the dispersion material by capillaryattraction outwardly through the mold pores y and evaporation attheouter mold surface portions, drying the deposited layerings by capillaryattraction until substantially all water has been removed therefromthrough the mold pores, opening the mold, and removing the articletherefrom.

6. A seamless hollow article produced by the method of claim 2.

7. A seamless hollow article produced 'by the method of claim 3, theoutside of the article bearing the impressions of the mold surfaceportions, the article being of substantially accurately uniand beingadapted to be opened and closed, placing in said article-forming cavityaV predetermined quantity of aqueous dispersion material capable of.setting by removal of water therefrom, and thereafter applying to saidclosed mold a series of compound rotary motions about a plurality ofangularly disposed axes to deposit said predetermined quantity of theaqueous dispersion material in successive accreted layerings over thesurface of the mold cavity in diverse'directions of flow of thedispersion material, whereby said deposition and accretionisaccomplished by removing Water from the dispersion .material bycapillary attraction outwardly through the mold pores and evaporation atthe outer mold surface portions, the steps of the method being carriedout while substantial proportions of the outer mold surface portions areconstantly exposed to atmosphere of relatively lower humidity than theatmosphere within the mold cavity, whereby the mold cavity surfaceportions will be maintained constantly wetter than said outer surfaceportions thereof andwhereby the water from the dispersion material willbe continuously dissipated outwardly of the mold cavity by saidcapillary attraction and evaporation. l

9. A method of making hollow articles comprising the steps of providinga sectional porous mold having an article-forming cavity adapted tocontain a liquid in all positions of rotation thereof and being adaptedto be opened and closed, placing in said article-forming cavity apredetermined quantity of latex aqueous dispersion material capable ofsetting by removal of water therefrom, and thereafter applying to saidclosed mold a series of compound rotaryA motions about a plurality ofangularly disposed axes to deposit said predetermined quantity of theaqueous dispersion material in successive accreted layerings over thesurface of the mold cavity in diverse directions of now of thedispersion material, whereby said deposition and accretion isaccomplished by removing water from the dispersion material by capillarylattraction outwardly through the mold pores and evaporation at theouter mold surface portions, the stepsv of the method being carried outwhile substantial proportions of the outer mold surface portions areconstantly exposed to atmosphere of relatively lower humidity than theatmosphere within the mold cavity, whereby the mold cavity surfaceportions will be maintained constantly wetter than said outer surfaceportions thereof and whereby the water from the dispersion material willbe continuously dissipated outwardly of the mold cavity by saidcapillary attraction and evaporation.

10. A method of making hollow articles ccmprising the steps of providinga sectional porous mold having an article-forming cavity adapted tocontain a liquid in all positions of rotation thereof and being adaptedto lbe opened and closed, placing in said article-forming cavity apredetermined quantity of aqueous dispersion material capable of settingby removal of water therefrom, thereafter applying tosaid closed mold aseries of compound rotary motions about a plurality of angularlydisposed axes to deposit said predetermined quantity of the aqueousdispersion 12 material in successive accreted layerings over the"surface of the mold cavity in diverse directions of flow of thedispersion material, whereby said deposition and accretion isaccomplished by removing water from the dispersion material by capillaryattraction outwardly through the mold pores and evaporation at the outermold surface portions, retaining the resulting fully-formed article inthe mold until it has become sufilciently set by continued capillaryattraction and evaporation to permit removal of the article withoutdamage thereto, removing the article from the mold, and exposing thearticle to open drying A temperature.

1l. A method of making hollow articles comprising the stepsof-.providing a sectional porous mold having an article-forming cavityadapted to contain a liquid in all positions of rotation thereof andbeing adapted to be opened and closed, placing in said article-formingcavity a predetermined quantity of latex aqueous dispersion materialcapable of setting by removal of water therefrom, thereafter applying tosaid closed mold a series of compound rotary motions about a pluralityof angularly disposed axes to deposit said predetermined quantity of thelatex aqueous dispersion material in successive accreted layerings overthe surface of the mold cavity in diverse directions of flow of thedispersion material, whereby said deposition and accretion isaccomplished by removing water from the dispersion material by capillaryattraction outwardly through the mold pores and evaporation at the outermold surface portions, retaining the resulting fully-formed article inthe mold until it has become suiciently set by continued capillaryattraction and evaporation to permit removal of the article withoutdamage thereto, removing the article from the mold, and exposing thearticle to heat of vulcanization, an aperture being provided through thewall of the article prior to the vulcanizing step.

12. A hollow article produced by the method of claim 11.

.13. A method of making hollow articles comprising the steps ofproviding a sectional porous mold having an article-forming cavityadapted to contain a liquid `in all positions of rotation thereof andbeing adapted to be opened and closed, said mold being provided with aprotuberance of substantially non-porous material extended into the moldcavity from' the surface thereof, placing in said article-forming cavitya predetermined quantity of aqueous dispersion material capableofsetting by removal of Water therefrom, and thereafter applying to saidclosed mold a series of compound rotary motions about a plurality ofangularly disposed axes to deposit said predetermined quantity of theaqueous dispersion material in succesive accreted layerings over thesurface of the mold cavity in diverse directions of flow of thedispersion material, but excluding the portion of. the mold cavityoccupied by said non-porous protuberance, whereby said deposition andaccretion is accomplished by removing water from the dispersion materialby capillary attraction outwardly through the mold pores and evaporationat the outer mold surface portions, said non-porous protuberance, bypreventing accretion of the dispersion material in said excluded portionof the mold cavity surface thereby forming an opening in the-wall ofthe` article.

13 mold having an article-forming cavity adapted to contain a liquid inall positions of rotation thereof and being adapted to be opened andclosed, placing in said article-forming cavity a predetermined quantityof latex aqueous dispersion material capable of setting by removal ofthe water therefrom, and thereafter applying to said closed mold aseries of compound rotary tinued capillary attraction and evaporation topermit removal of the article without damage thereto, the foregoingsteps of the method being carried out while a major proportion of theouter surfaces of the mold is exposed to the evaporative action andunder controlled conditions whereby the mold will be maintainedconstantly Wetter at the cavity surface portions thereof than at saidexteriorly exposed surface portions of the mold and whereby the waterfrom the dispersion material will be continuously dissipated outwardlyof the mold cavity by said capillary attraction and evaporation,removing the article from the mold, and exposing the article to openheat of vulcanization, an aperture being provided through the Wall ofthe article prior to the vulcanizing step.

15. Apparatus for producing hollow articles by deposition of aqueousdispersion material, comprising a plurality of sectional cavity molds ofporous material each having at least one articleforming cavity thereinadapted to contain predetermined quantities of the dispersion materialin all positions of rotation of the molds, a mold support having guidemeans for removably retaining said molds in stacked relation, releasableclamping means on said support for clamping the molds in said stackedrelation in said support, spacer means between adjacent molds of thestack, said support and spacer means being proportioned to provide forexposure of the pores of the molds over substantial proportions of theouter surface areas of the molds including the spaced adjacent surfacesof the same, means for 14 mounting said mold support to be rotatableabout a plurality of angularly disposed axes to apply compound rotarymotion to said mold stack, and means operable to apply said compoundrotary motion to said mold support to deposit predetermined quantitiesof dispersion material in successive accreted layerings over thesurfaces of the respective article-forming cavities, by capillaryremoval of water from the dispersion material outwardly through the moldpores and evaporation at said exposed outer mold surface areas.

16. A method of making hollow articles vcomprising the steps ofproviding a sectional porous mold having an article-forming cavityadapted to contain a liquid in all positions of rotation and having anon-porous portion to be presented inwardly of the mold cavity surface,placing in said article-forming cavity a predetermined quantity ofaqueous dispersion material capable of setting by removal of the watertherefrom, and thereafter applying to the mold a series of compoundrotary motions about a plurality of angularly disposed axes to depositsaid predeterminedA quantity of the solution in successive accretedlayerings over the surfaces of the mold cavity in diverse directions offlow of the dispersion material, whereby said deposition and accretionis accomplished by/removing Water from the dispersion material bycapillary attraction outwardly through the rnold pores and evaporationat the outer mold surface portions, said deposition of dispersionmaterial by being substantially ineffective as to said non-porousportion thereby providing a corresponding void in the .wall of thearticle.

DIETRICH G. REMPEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 50,957 Richardson Nov. 14, 18651,341,670 Powell June 1, 1920 1,812,242 Jensen June 30, 1931 2,153,184Hogen Apr. 4, 1939 2,161,281 Carter June 6, 1939 FOREIGN PATENTS NumberCountry Date 416,824 Great Britain Sept. 21, 1934

